Thread: L322 td6 GM transmission oil & filter

Yeah, everyone has something to say about these boxes, and a lot of it is garbage. If someone does come up with a reliable and HD solution, there will be a lot of people standing in the queue. It would be great to unleash a bit more power from the engne, but I'm just too scared to try...

I'm still serious about putting a manual box in mine. I think I have most of the angles covered, but there is still some info that no one can help with - I guess eventually I'll just do it, and sort out the gaps as I go...

I think within a few years, there will be some people try something different, as these cars become cheaper and the older and high km ones are picked up cheap, someone will have a crack at something different, as rebuilding or replacing these boxes long term just won't be viable.

Cheers - Gav

Why arnt aussie GM boxes having troubles in commodores? Is it because they can't handle the torque of the diesel?

Originally Posted by Camo

Why arnt aussie GM boxes having troubles in commodores? Is it because they can't handle the torque of the diesel?

Simple - they DO have problems in the Dunny Door - you only have to ask a transmission specialist to have them tell you they are all a piece of ****. Not sure what's in the POS Commodore I have, but that is playing up after 65KKM, as are many others in our fleet...

Originally Posted by Laurie

The 5L40E is the achilles heel of the Td6 L322

How is the 5L40E the "Achilles heel"?

I have now done 180k in mine - I regularly use it to tow 3 tonne loads which always include a 10 km section of steep mountainous climb from seal level to 800m ASL. Every time I drive I drive at least 10 km of rough mountainous track and then do 160 kph for sections as well. I use manual selection for all braking or slowing down for curves. I have owned the truck since new and have not changed the ATF or filter. I bought those to do a couple of years ago but have not got around to it yet - maybe I'll do them at 200k.

Originally Posted by Laurie

This is taken from a US GM Auto rebuilder, the US rebuilders have a there own oil preferences and service advice.

"BMW X5 and Land Rover Discovery’s with the 5L40E transmission are known for failing due to over working the transmission. As they are classed as a sealed Transmission the oil often goes off like milk left in the sun and causes the internals to fail. Transmission Rebuilders recommend servicing these transmissions every 20,000kms or 12 Months which every accrues first."
Recommended Oil is Dexron 111 however there are better oils available now.

Valvoline Dexron 6
Valvoline Maxlife (Synthetic)
Castrol Transmax (Full Synthetic)

This quote is from an Australian website 'Furitech Automotive' and not a "US GM auto rebuilder". It just confirms that you should not believe all that you find on the web. Like everything in life - caveat emptor

Originally Posted by Daniel

How is the 5L40E the "Achilles heel"?

I have now done 180k in mine - I regularly use it to tow 3 tonne loads which always include a 10 km section of steep mountainous climb from seal level to 800m ASL. Every time I drive I drive at least 10 km of rough mountainous track and then do 160 kph for sections as well. I use manual selection for all braking or slowing down for curves. I have owned the truck since new and have not changed the ATF or filter. I bought those to do a couple of years ago but have not got around to it yet - maybe I'll do them at 200k.

I think you have been lucky - every forum in the world that deals with the L322 has numerous threads on failed transmissions. I wish everyone the best who has had no dramas with theres, but all the research I did before I bought one showed this to be one of the major weak points in the car, and after I bought one, I found out first hand how weak they are. They are under speced for this vehicle in terms of HP and torque they can manage, they have notorious weak components - coupled with that LR's advise that they were 'sealed for life' so no one did anything to theirs. There are heaps failing at about 160KKM (100K Miles) and there are plenty out there reaching this milestone. There is so much to love about these cars, but the trannie aint one of them...

Cheers - Gav

Originally Posted by bacicat2000

Yeah, everyone has something to say about these boxes, and a lot of it is garbage. If someone does come up with a reliable and HD solution, there will be a lot of people standing in the queue. It would be great to unleash a bit more power from the engne, but I'm just too scared to try...

I'm still serious about putting a manual box in mine. I think I have most of the angles covered, but there is still some info that no one can help with - I guess eventually I'll just do it, and sort out the gaps as I go...

I think within a few years, there will be some people try something different, as these cars become cheaper and the older and high km ones are picked up cheap, someone will have a crack at something different, as rebuilding or replacing these boxes long term just won't be viable.

Cheers - Gav

I'm not convinced that the issue with the 5L40E 'failures' that some experience has to do with under rating for power/torque. From my research it is more to do with incorrect lubrication of the the valve bodies. Valve bodies are usually the weak link in most auto transmissions. I suspect that many L322 5L40E failures are probably due to good intentions, replacing the 'factory sealed' ATF with some you beaut synthetic ATF that is not to the correct GM specs. The guys in GB where these 5L40E issues first surfaced have confirmed that the problem is with incorrect lubrication causing fast tracked wear in the valve bodies. That is why the correct ATF is so critical and that is why it is better to leave the factory ATF in there rather than replacing it with new yet incorrect spec ATF.
In my other RR ('89 Classic) I run a 6.5 turbo GMC motor that puts out more torque/power than the BMW td6. I run a GM T700 transmission. The standard mod for that unit is to make modifications to the valve body and failures once again always occur in the valve body - nothing to do with torque/power ratings as such.
To put a manual transmission in the L322 would be shame and probably spoil the whole vehicle. You might as well just buy some cheap Jap crap as they still come with dark age technology such as manual transmissions.
Carrying out a reco on the 5L40E every 200k kms (if that's indeed what it takes) makes far more sense than playing around with a manual.

Sorry Dan, but we'll have to agree to disagree. While I would imagine that incorrect fluid would have caused some failures, a lot of them have failed while they still have the original fluid in them - I have read 100's of posts about this both before and after my own trannie **** itself, and it is not just the valve bodies that are a potential weak point in these. The torque converter is also a major culprit, as well as the pump. To a lesser extent the frictions are also highly stressed behind this engine - and are one of the components that are maxed out in this application. I have done A LOT of research on these boxes - they are not able to be fully bullet proofed when rebuilt, but there are a few good mods that are possible - I have an uprated torque converter in mine now, as well as better valves in the valve body that will seal better in worn bores. I also have larger frictions on some of the gears. I still don't trust it as far as I can throw it though... It will take me a loooong time to trust this box again.

Just on your TH700 box - that box has HEAPS bigger frictions in it than the 5L40E, so you aint going to break that through overpowering it. If I could fit one of those in behind the TD6, it would be a much better option that that piece of plastercine that is there now. You said everything with the last line of your post - "Carrying out a reco on the 5L40E every 200k kms (if that's indeed what it takes) makes far more sense than playing around with a manual." A gearbox - auto or manual should be able to survive longer than 200KKM between rebuilds on a standard vehicle. The very fact so many of these fail - for whatever reason tells the story. It just wasn't the best decision LR made when developing this car.

Do you work for GM or something - I haven't come across such a staunch supported of their gearboxes before.

As for the manual conversion - each to their own - I much prefer to drive a manual over an auto any day of the week - and I drive a lot of KM both in the city and the country, and I would have my manual Transit van back in a flash over the sludge box dunny door I have to drive now for work.

I don't think a manual would ruin it - Range Rovers have been available with manual gearboxes before - I have one in the driveway.

Cheers - Gav